Dolos Brings Lightweight Rust-Based Data Node to Cardano Developers

Cardano Developers Office Hours hosted Santiago Carmuega, CEO and founder of TxPipe, for a technical presentation on Dolos, a lightweight Cardano data node written in Rust. The session focused on infrastructure diversity, modularity and easier access to Cardano blockchain data for applications, wallets and backend services.

Dolos was presented as a complementary tool, not a replacement for the existing Cardano node. Its purpose is narrower, providing a flexible query layer for teams that need reliable chain data without operating a full infrastructure stack.

Dolos Targets Cardano Developer Experience and Data Access

TxPipe builds open source tooling for Cardano developers, and Dolos fits into that broader focus on improving developer experience. Carmuega said one of the first pain points he encountered in the Cardano ecosystem was the difficulty of getting data from the node.

In some blockchain ecosystems, developers can query an endpoint and receive information about the latest block, a transaction or an address state. In Cardano, that process is more technically demanding because it involves Ouroboros mini protocols, binary formats and a custom networking model.

According to the presentation, Dolos was created as an alternative and complementary node for a specific use case, giving developers a richer and more flexible way to query data from the Cardano chain. That makes it relevant for teams building applications, wallets and data services that do not need to participate in consensus or produce blocks, but still require a stable backend for reading chain data.

Carmuega also compared Dolos with DB Sync. DB Sync remains a common tool for deep SQL-based access to Cardano data, but it requires a Cardano node, PostgreSQL and a synchronization worker. Dolos targets use cases where applications already know the specific data they need and can use more efficient APIs instead of operating a full dynamic SQL backend.

Rust-Based Cardano Node Supports Blockfrost, Kupo and UTXRPC

Dolos exposes several API surfaces for external applications. One of them is a gRPC interface using the UTXRPC specification, designed for use cases where compact binary communication and low-latency queries matter. Dolos also includes an API shaped like Blockfrost, allowing teams that already use Blockfrost-style endpoints to point existing applications toward Dolos with fewer integration changes.

TxPipe said it has worked closely with the Blockfrost team and has used Blockfrost conformance tests to check endpoint compatibility. According to Carmuega, Dolos passes more than 900 conformance tests, although it does not support every Blockfrost endpoint because some were excluded after a cost-benefit review.

Dolos also provides a mini Kupo API focused on the UTXO set, datums and scripts, using query patterns familiar to Kupo users. In addition, it exposes Cardano node-to-client mini protocols, including local state queries and chain sync. That allows certain tools expecting interaction with a Haskell node to connect to Dolos and use part of the same API surface.

This design positions Dolos as an infrastructure adapter for Cardano applications. Wallets, transaction builders, explorers and middleware tools can use different access patterns depending on whether they need Blockfrost compatibility, Kupo-style UTXO queries, UTXRPC performance or a socket interface closer to a standard Cardano node environment.

Sliding Window Storage and Relay Node Trust Assumptions

Dolos includes clear trade-offs. Carmuega said Dolos does not perform full consensus or full block validation when pulling data. Instead, it connects through node-to-node protocols to a relay node, either local or public, selected by the operator as the source of data. That creates a trust assumption between Dolos and the relay node being used.

For application developers, that model can fit data access use cases where a team does not need to run a complete local node stack. The comparison made during the session was that DB Sync also depends on a node in the background for its data source, while Dolos can connect to a relay node without requiring a local Haskell node socket.

One technical feature highlighted in the presentation is Dolos’ sliding window storage model. Operators can keep the full history of the chain, but they can also choose a limited time window. In that setup, Dolos retains blocks, transactions, scripts, datums and UTXO data relevant to the selected period while older data is removed from local storage. This can reduce disk requirements for applications that only need recent chain activity rather than the full history from the Byron era.

TxPipe also showed performance data from mainnet Dolos instances. According to the dashboard shown during the session, one instance was handling around 180 requests per second, with the 99th percentile latency mostly below 800 milliseconds and the 50th percentile around 4 to 5 milliseconds. Carmuega connected those results to Dolos being a compact single-process Rust component, combined with local key-value storage, LSM trees, bloom filters and specific indexing strategies.

The presentation included practical examples of Dolos in use, including Lace Anatomy, a developer-focused chain explorer running on Dolos as its backend without DB Sync. Carmuega also mentioned Demeter platform endpoints and other Cardano ecosystem teams using Dolos under the hood for data access.

Dolos gives Cardano applications a backend option that can serve Blockfrost-like, Kupo-like and UTXRPC access patterns without requiring DB Sync for every use case. For wallets, explorers and data services, the operational difference is a lighter route to Cardano chain data when full consensus participation is not part of the infrastructure requirement.